Surface finishing and treating method



Sept. 22, 1964 c. E. NOLAN 3,149,445

SURFACE FINISHING AND TREATING METHOD Original Filed Sept. 25, 1959 2 Sheets-Sheet 1 INV EN TOR.

(31.40015 ,5. A/OL/Vl/ BY dead,

p 22, 1964 r c. E. NOLAN 3,149,445

SURFACE FINISHING AND TREATING METHOD Original Filed Sept. 25, 1959 2 Sheets-Sheet 2 J0 a Z V .55

-1 r fi 6 2" AAA" E 12 INVENTOR. (14 up; 5- A/0A4A/ United States Patent 3,149,445 SURFACE FINISH-ENG AND TREATWG METHOD Claude E. Nolan, Bridgeton, NJL, assignor to Owens- Iilinois Glass Company, a corporation of Ghio Original application Sept. 25, 1959, Ser. No. 842,264, now

Patent No. 3,133,765, dated Sept. 17, 1963. Divided and this appiieation Dec. 7, 1262, Ser. No. 243,067

6 t'llairns. (Ci. 51319) This application is a division of applicants copending application Serial No. 842,264, filed September 25, 1959, now Patent No. 3,103,765, dated September 17, 1963.

The present invention relates to an improved slurry surface finishing and treating method, and more particularly to an improved method wherein the surface finishing is accomplished by utilizing a powerful stream of fluid borne abrasive material in slurry form.

Among other important objects, it is a principal object of the present invention to provide an improved method employing an abrasive slurry of the aforementioned type for producing a surface finish of extreme smoothness on articles subjected to such slurry.

Another object of this invention is to provide a method capable of accomplishing the surfacing operation and the subsequent cleaning and corrosion inhibiting operations in an economical manner and in such a manner as to substantially reduce the waste and loss of abrasive slurry and treating mediums utilized.

A further object of the present invention is to provide a method for accomplishing such slurry blasting and surface cleaning and treating at one convenient location whereby the entire surface finishing operation can be effected rapidly and with a minimum of movement of the articles being resurfaced and finished.

A still further object of this invention is to provide a method for maintaining the fluid borne abrasive in thoroughly agitated and homogeneously suspended condition with its fluid carrier during the surfacing operation.

A still further objective is to provide an improved method for removing and reusing the residual slurrious abrasive remaining on the slurry-blasted article or workpiece subsequent to the slurry blasting operation.

A still further objective is to provide a method for treating the slurry-blasted surfaces of the workpiece with a corrosion inhibiting medium immediately following the slurry blasting and washing operations and to recapture the medium for reuse.

Another particular object of the present invention is to exhaust the slurry blasting chamber during the slurry blasting operation to remove the vapors and fine air-borne abrasive material from within the chamber and return same to the main slurry supply.

A more specific object of this invention is to provide a method for easy movement of the workpieces into the blasting chamber through an access opening therein and in such manner that such movement will also close the access opening when the workpieces are positioned within the blasting chamber.

Other objects and advantages will become apparent from the following detailed description taken in conjunction with the accompanying drawings upon which a preferred embodiment of the apparatus selected for performing the present invention is illustrated, and wherein:

FIG. 1 is a schematic front perspective view of apparatus embodying the present invention; and including a cabinet enclosure for the slurry blasting operation and adjacent washing and surface treating stations; and

FIG. 2 is a vertical sectional view along the plane IIII in FIG. 1 and taken through the viewing window in the cabinet enclosure; and

FIG. 3 is a fragmentary vertical sectional view of the ice bottom portion of the cabinet enclosure with the workpiece carrier in position within the slurry blasting chamber.

Generally, the invention is shown embodied in apparatus commonly referred to as Wet blasting or slurry blasting apparatus in cooperative association with washing and surface treating apparatus, the latter effecting a washing and treating of the workpiece after it has been subjected to the blasting operation. Referring particularly to FIG. 1, the blasting operation is carried out within a cabinet enclosure 10. Thereafter, the workpiece is transferred to a washing station designated as A and which is located adjacent to the cabinet enclosure 10. Following the washing operation the workpiece is removed to a treating station designated as B and situated adjacent to washing station A. The movement of the workpiece or group of workpieces between the stations A and B and the cabinet enclosure It is conveniently ac complished by means of a wheeled dolly 11 which rides on tracks 12 running between stations A and B and into the interior of the cabinet enclosure 10 through an access opening in the side wall thereof adjacent to station A. Hence, the workpiece or group of workpieces may be placed on the bed of the dolly 11 and wheeled thereon into the cabinet enclosure 10 wherein the blasting operation is performed to remove scale, rust, dirt, etc. from the surfaces of the workpiece. Thereafter, the dolly 11 may be withdrawn from the cabinet enclosure 10 and wheeled along tracks 12 to station A where the workpiece is thoroughly washed and rinsed to remove foreign material adhering to the polished surfaces thereof including residual slurry and abrasive material remaining thereon from the wet blast operation. Following a thorough washing, the dolly 11 is wheeled to station B where the washed workpieces are preferably treated with a corrosion inhibiting medium in order to protect the newly polished and exposed surfaces thereof.

A preferred form of construction of the cabinet enclosure 10 is illustrated in FIG. 1, the illustrated enclosure being of a type well-known in the art and comprising a hollow interior blasting chamber 13 emptying into a hopper 14 at the base of the enclosure; a viewing window 15 formed in the front wall of the cabinet enclosure which permits the operator to View the blasting operation; and arm openings 16 formed in the front wall of the enclosure which provide access into flexible waterproof sleeves 17 extending into the blasting chamber and having gloves 18 on the inner extremities thereof which permit the operator of the apparatus to grasp and manipulate the workpieces and the blasting gun 20 which is suspended within the interior of the blasting chamber 13. The roof 21 of the blasting chamber 13 is provided with an outlet opening around which is connected an exhaust line 22 which withdraws vapors and dust from the interior of the blasting chamber which occur while the blasting operation is in progress.

As best illustrated in FIG. 2, the aforementioned viewing window 15 is preferably inclined downwardly and inwardly and receives a constant spray of wash water on the interior surface thereof to remove dirt and slurry deposits from the window and to better enable the operator to view the blasting operation. The spray of wash water is received on the viewing Window 15 from spray nozzles 23 which are positioned at several closely spaced locations across the breadth of the window and disposed toward a window. Valved water lines 24 and 25 are connected to the spray nozzles 23 and pipe the wash water thereto from a suitable water supply line, not illustrated. As the wash water runs down the inclined viewing window 15, it is trapped in a horizontal trough 26 disposed lengthwise along the lower margin of the viewing window. A receiving lip 27 on the edge of the trough 26 3 in contact with the window directs the wash water into the trough. The trough 26 feeds to a drain pipe 28 which in turn disposes of the wash water in a suitably located drain, not illustrated.

The blast gun 20 from which is emitted a pressurized jet of abrasive slurry may be of conventional construction well known in the art and has inlet ports 29 and 36 leading to the barrel of the gun. Ports 29 and 30 are respectively connected with flexible hoses 32 and 33 which deliver compressed air and slurry to the gun 20 to form the liquid blasting jet. Also, the hoses 32 and 33 are connected at their opposite ends to pipes 34 and 35, respectively. Pipe 34, which supplies slurry to the gun 29, passes through the wall of the cabinet enclosure 10 and leads down to and through the wall of the slurry hopper 14 where it emerges into the interior of the hopper at location disposed well beneath the surface level of the slurry 36 contained therein, for example, as shown in FIG. 3. The pipe 35 supplying compressed air to the blast gun 2t), likewise, preferably runs through the wall of the cabinet and the passage of compressed air therethrough is controlled by a suitable foot valve 37 conveniently located near the foot of the operator. Although normally closed, the foot valve is constructed to open when the operator presses his foot down upon the spring loaded foot lever 38 which is operatively connected to a lever arm 39 on the valve 37 (FIG. 1) by linkage 40. The foot lever 38 is likewise linked to a lever arm 41 on a switch box 42 which provides an onoff electrical switch for the motor 43 operating the slurry sump pump 44 which pumps slurry from the hopper 14 through pipe 34 to blast gun 20. When the foot lever 33 is depressed the lever arm 41 closes the electrical circuit in the switch box 42. Thus, electrical wires 45 and 46 leading from the switch box 42 to the motor 43 actuate the later when the foot lever 38 is depressed thereby causing slurry to be pumped to the blast gun 20 concurrently with the admission of compressed air to the gun.

The slurrious abrasive utilized in the blasting operation may be of the conventional types and depends in large measure upon the degree of smoothness desired to be produced on the workpiece. For example, a fine mesh silica of about 300 mesh screen size mixed in a water carrier and having a consistency ranging from an extremely fluid or watery slurry to a fluid mud may be employed with varying degrees of success depending upon the quality and texture of finish desired. Commercially available abrasives such as Hydrosil Arkansas Abrasive sold by the Hydrapone Equipment Company or KXX240 Aluminum Oxide sold by the Carborundum Company are suitable in most instances where an extremely fine finish is desired. Obviously, many types of fine abrasives may be employed and the invention herein is not intended to be limited to those types of abrasives disclosed.

The exhaust system which draws vapors through the exhaust line 22 from the cabinet enclosure and thereby ventilates and effectively reduces fog in the cabinet enclosure will now be described in detail. During the blasting operation moisture and moist vapors in large part composed of the fine abrasive material and dust are generated in the blasting chamber 13. The exhaust system comprises a motor driven centrifugal air displacement pump 48 or other suitable vacuum pump connected in the exhaust line 22. An exit pipe 50 at the outlet end of the exhaust line 22 discharges the exhausted vapors into the hopper 14 at a location substantially beneath the surface level of the slurry supply 36. A vent line 51 extending from exit pipe 50 between the pump 48 and hopper 14 to the atmosphere or suitable disposal apparatus, not illustrated, is provided with a damper 52 which together with another similar damper 53 located in the exit pipe 50 near the hopper 14 serves to control the amount of exhausted vapors returned to the 4 slurry 36. By manual or other adjustment of the dampers 52 and 53 the exhaust vapors may be in part discharged into the slurry 36 and in part vented or may be entirely vented or discharged into the slurry 36.

The wheeled dolly 11 upon which the workpieces are placed prior to being moved into the cabinet enclosure 1% comprises a horizontal rectangular bed 55 carried upon rotatable wheels 56 disposed at spaced locations along opposite sides of the bed and riding on the tracks 12; a vertical side splash wall 57; and a vertical back plate 58. The back plate 58 is constructed and arranged to form a door for the access opening at 60 in the side of the cabinet enclosure 10 when the dolly is wheeled into the blasting chamber 13 and is provided with a suitable handle 59 for easy manual manipulation of the dolly along the tracks 12. As shown in FIG. 3, when the dolly is wheeled into the cabinet enclosure 10 the back plate 58 contacts and forms a snug fit with the wall of the cabinet enclosure immediately around the acess opening 65). Where desired, a gasket or other suitable sealing material may be employed between the mating surfaces of the back plate 53 and wall area around the access opening 60. The bed 55 of the dolly 11 is preferably of an open-work or lattice structure and may be constructed of wire mesh 62. Wheel blocks 63 securely mounted on the edge of the bed 55 have rotatable stub shafts 64 journalled therein on bearings which carry the wheels 56.

After the workpieces or material have been blasted with abrasive emitted slurry from the blast gun 20 until the desired surface finish has been obtained, the dolly 11 with the workpieces thereon is wheeled from the cabinet enclosure 10 along the tracks 12 to station A where the workpieces are thoroughly washed or rinsed to remove residual slurry and such other foreign matter as may remain on the surfaces of the workpieces. The Washing operation preferably utilizes tap water or other suitable washing medium which is sprayed from an overhead spray gun 66 or other suitable means for directing a stream or spray onto the workpiece. The'spray gun 66 is operatively attached to a flexible hose 67 coiled around a retractable roller 68 and connected to a conduit 6? leading to a supply source (not shown) of wash water or other washing medium. Beneath the tracks 12 and disposed under the spray gun 66 is a catch basin 76 having a drain pipe 71 leading to a separator which is shown as a motor driven centrifuge 72. The centrifuge 72 empties into a drain line 73 and a slurry return line 74. The drain line 73 leads to a suitably disposed drain or waste receptacle and the return line 74 feeds to the hopper 14 beneath the surface level of the slurry 36. The centrifuge 72 functions as a separator and dispels excess wash water which would otherwise dilute the residual slurry washed down from the workpieces. The slurry, on the other hand, drains from the centrifuge and is pumped back to the main slurry supply contained in the hopper 14.

After the workpieces have been thoroughly washed at station A, the dolly 11 is transferred along tracks 12 to station B where a corrosion inhibiter is applied to the washed and finished surfaces of the workpieces. The corrosion inhibiter, which may be any conventional antirust solution or the like is sprayed from an overhead spray gun 76 which receives a suitable corrosion inhibiting medium through a flexible hose 77. The hose 77 is coiled around a retractable roller 78 suitably mounted overhead and extends therefrom to a storage tank 79 supported at an elevation substantially above the spraying position and storing a supply of the corrosion inhibiting medium. Beneath the spray gun 76 and the track 12 there is a catch basin 80, similar to the catch basin beneath station A, which traps the excess corrosion inhibiting medium draining from the workpieces and passing through the openings in the dolly bed 55. Communicating with the catch basin S0 is a valved drain line 81 in which'there is a suitable fluid pump, such as a centrifugal pump 82, which returns the excess corrosion inhibiting medium through the return line 83 to the overhead storage tank 79.

During periods of idleness in the use of the slurry blasting apparatus it is quite common for the abrasive constituents of the slurry to precipitate to the bottom of the hopper 14. Accordingly, a compressed air line 84, leading into the lowermost portion of the hopper 14 from a valved feed line 85, affords means for alleviating the sedimentation problem arising from such precipitation. As illustrated, the valved feed line 85 may also be utilized to supply compressed air to the air line 35 leading to the blast gun 20. Hence, by admitting compressed air into the lowermost portion of the hopper 14 from air line 84 prior to pumping the slurry 36 to operating the blast gun 20, the sediment collected therein will be violently agitated and resuspended Within its water carrier.

From the foregoing it will be readily apparent that the exhaust system avoids loss and waste of the slurry by enabling the exhausted vapors and air borne abrasive particles to be returned to the slurry hopper for reuse. Additionally, the arrangement of the exhaust system is such that the exhausted vapors and abrasive particles are discharged under positive pressure into the slurry 36 through an outlet opening or discharge opening in the hopper 14 at a location well beneath the surface level of the slurry 36. Consequently, the slurry 36 may be maintained in a well agitated and homogeneously mixed condition during the use of the slurry blasting apparatus.

It will also be apparent that the workpieces may be transferred quickly and conveniently into and out of the blasting chamber 13 by the dolly 11. Also, the entire slurry blasting or surface finishing, washing and corrosion inhibiting operations may be performed with little effort by a single operator within a very small working area and with only limited movement of workpieces. The dolly, upon which the workpieces are transferred, in addition to increasing the efiiciency of the operation and reducing the time expended to completely finish, wash and treat the workpieces is constructed to cooperate with the cabinet enclosure and function to close the access opening 60 in the side of the cabinet enclosure. Thus, the necessity of closing a door to confine the slurry within the blasting chamber 13 during the slurry blasting operation is obviated and the physical movements and operations performed by the operator are reduced. Thus, more time is available for productive efforts on the part of the operator of the apparatus.

Although the present invention has been described in substantial detail in the foregoing description, it is not intended that the invention be limited to such details, or otherwise, than is necessitated by the scope of the appended claims. Having now described the invention in full detail, I claim:

1. In the method of slurry blasting a workpiece to produce a smooth finish thereon and including the steps of blasting the workpiece with a jet of abrasive slurry in an enclosed chamber, trapping the spent jet of slurry in a slurry storage chamber, and withdrawing said slurry from said storage chamber to repeat said blasting step, the improvement comprising the steps of exhausting said enclosed chamber during said blasting step, and discharging the exhaust into the trapped slurry in said storage chamber under sufficient force to substantially agitate said slurry.

2. In the method of slurry blasting a workpiece to produce a smooth finish thereon and including the steps of blasting the workpiece with a jet of abrasive slurry in an enclosed chamber, trapping the spent jet of slurry in a slurry storage chamber, and withdrawing said slurry from said storage chamber to repeat said blasting step, the improvement comprising the steps of exhausting said enclosed chamber during said blasting step, discharging the exhaust into the trapped slurry in said storage chamber under sufiicient force to substantially agitate said slurry, and selectively controlling the discharging force of said exhaust into said storage chamber to control the extent of agitation of the slurry therein.

3. In the method of slurry blasting a workpiece to produce a smooth finish thereon and including the steps of blasting the workpiece with a jet of abrasive slurry in an enclosed chamber, trapping the spent jet of slurry in a slurry storage chamber, and withdrawing said slurry from said storage chamber to repeat said blasting step, the improvement comprising the steps of exhausting said enclosed chamber during said blasting step, discharging the exhaust into the trapped slurry in said storage chamber under sufficient force to substantially agitate said slurry, and selectively venting a portion of said exhaust during said exhausting step to control the discharging force of said exhaust into said storage chamber.

4. In the method of surface finishing a workpiece to produce a smooth finish thereon, the steps of blasting the workpiece with a jet of abrasive slurry, trapping the spent jet of slurry in a slurry storage chamber, and withdrawing said slurry from said slurry storage chamber to repeat said blasting step, the improvement comprising the steps of washing the workpiece with a washing medium to remove abrasive slurry adhering thereto, trapping the washings, separating the removed abrasives from said Washing medium, and returning the abrasives to said slurry storage chamber.

5. In the method of surface finishing a workpiece to produce a smooth finish thereon, the steps of blasting the workpiece at a slurry blasting station with a jet of abrasive slurry, trapping the spent jet of slurry in a slurry storage chamber, and withdrawing said slurry from said slurry storage chamber to repeat said blasting step, the improvement comprising the steps of transferring the slurry-blasted workpiece to a washing station adjacent to said slurry blasting station, washing the workpiece at said washing station with a washing medium to remove abrasive slurry adhering thereto, trapping the washings, separating the removed abrasives from said washing medium, and returning the abrasives to said slurry storage chamber.

6. In the method of surface finishing a workpiece to produce a smooth finish thereon, the steps of blasting the workpiece at a slurry blasting station with a jet of abrasive slurry, trapping the spent jet of slurry in a slurry storage chamber, and withdrawing said slurry from said slurry storage chamber to repeat said blasting step, the improvement comprising the steps of transferring the slurry-blasted workpiece to a washing station adjacent to said slurry blasting station, washing the workpiece at said washing station with a washing medium to remove abrasive slurry adhering thereto, trapping the washings, separating the removed abrasives from said washing medium, and returning the abrasives to said slurry storage chamber, transferring said workpiece to a corrosion inhibiting station adjacent to said washing station, emitting a corrosion inhibiting medium onto said workpiece, and thereafter trapping said corrosion inhibiting medium and recirculating the same for reuse.

References Cited in the file of this patent UNITED STATES PATENTS 293,011 Hall et al Feb. 5, 1884 1,643,175 Rich Sept. 20, 1927 2,576,008 Gladfelter et al Nov. 20, 1951 2,627,149 MacCracken Feb. 3, 1953 2,753,664 Garver July 10, 1956 2,763,964 Luce Sept. 25, 1956 2,815,716 Ransohoff Dec. 10, 1957 2,876,601 McFaddan Mar. 10, 1959 3,103,765 Nolan Sept. 17, 1963 FOREIGN PATENTS 612,200 Great Britain Nov. 9, 1948 

1. IN THE METHOD OF SLURRY BLASTING A WORKPIECE TO PRODUCE A SMOOTH FINISH THEREON AN INCLUDING THE STEPS OF BLASTING THE WORKPIECE WITH A JET OF ABRASIVE SLURRY IN AN ENCLOSED CHAMBER, TRAPPING THE SPENT JET OF SLURRY IN A SLURRY STORAGE CHAMBER, AND WITHDRAWING SAID SLURRY FROM SAID STORAGE CHAMBER TO REPEAT SAID BLASTING STEP, THE IMPROVEMENT COMPRISING THE STEPS OF EXHAUSTING SAID ENCLOSED CHAMBER DURING SAID BLASTING STEP, AND DISCHARGING THE EXHAUST INTO THE TRAPPED SLURRY SAID STORAGE CHAMBER UNDER SUFFICIENT FORCE TO SUBSTANTIALLY AGITATE SAID SLURRY. 